Setting up ANSYS Fluent Workflow

Setting up the
ANSYS Fluent workflow takes a series of different steps. To see how to make the
Fluent workflow in ANSYS, have a look into the Fluent tutorial that we have
uploaded recently. It covers all the sectors of on how to create the ANSYS
Fluent workflow and go about the aerodynamic testing of an object. After the ANSYS Fluent setup is completed, the user can move onto CFD-Post to carry out the
visual processing of the object to be tested.

Please note that
the CFD-Post can also be used along with
ANSYS CFX. The working principles of CFD-Post in ANSYS CFX are same as that in
ANSYS Fluent.

Starting CFD Post

This CFD-Post
ANSYS tutorial consists of three different methods of opening CFD-Post after
the ANSYS Fluent/CFX is all set-up, CFD-post can be opened by double-right-clicking
the ‘Results’ section at the end of the workflow or by left-clicking and edit as demonstrated in the image below;

Another method
to open CFD-Post is to create a standalone CFD-Post Session and link it with
your fluid flow simulation. Drag and drop session is usually used if your fluid simulation was created in a standalone session.

ANSYS
Fluent connected with CFD-Post

Another method
of opening your CFD-Post is by your start menu or command line. Go to;
Start>All programs>ANSYS 19.2>CFX. Once the CFX standalone version
opens, you can use it to open your CFD post as well.

GUI of ANSYS CFD Post

After the
CFD-Post starts up, you find the following window;

The opening
window of CFD-Post has the outline and other various tabs in the top-left
section of the window. This area is also the model tree for all the setups and
post-processing tools. The different views can also be selected and used
interchangeably.

CFD Post General Workflow

First, the user has to prepare the locations on
which the data will be extracted from or
the required plots.

The model above is a 2D cross-section of a water tank being tested for
the fluid flow once the water starts coming in it.

After the
locations are being set, the variables
and expressions are being set into the
system to extract the data. It must be noted
that the setting of the variables and expressions can be done via code input or by
selecting the commands from the fluent toolbar. After all the variables and
expressions are set, the user can
generate qualitative and/or quantitative
data at the locations. The reports for the results can then be generated in CFD-Post.

Setting and working with Locations

This ANSYS
tutorial also covers the details on setting
the locations in the CFD-Post and work on it. To create the locations, go to the insert menu or directly
click ‘locations’ from the toolbar. After the locations
are created, they will appear as entries
in the outline tree.

For the creation
of location, the domain, subdomain, mesh regions and boundary are also
available. The mesh regions and boundaries
can be edited and coloured by any
variable. Mesh regions allow the users to
access all available 2D/3D interior and
exterior regions from the mesh.

Types of Locations

There are several
different types of locations, and all are
covered in this ANSYS tutorial. All the different locations allow
users with more power in their hands to
test their product at all testing points. The types of locations and their descriptions are as follows;

Planes

The planes for locations are XY plane, YZ plane, ZX plane,
point and normal etc. The location can be bounded via solution domain(s).

Point

Another location
type is the ‘point’. By using points, the user can use XYZ coordinates to
select the location. The variable maximum and minimum number can also be used
to locate where the highest and lowest
values occur.

Point Cloud

Point cloud
allows the users to create multiple points and help users set up the locations.
The point cloud function is also used to create
seeds to create vectors, streamlines and more.

Lines

Lines, as the name suggests, helps
the users to create lines between
two points and carry out the post-processing.
Lines are commonly used as the basis for a graph plotting.

Polylines

Polylines are used in the creation of charts, extract a
line from a contour plot, read points from a file and use the line of intersection.

Volume

Volumes allow the users to select a 3D surface and
carry out the analysis using isovolumic, from surface and node functions.

Adding graphics objects

The graphics to
the object can be added to the object via the toolbar or the viewer right-click
menus. The most commonly used graphics are the streamlines, contours and
vectors. The vector plots can plot any vector variable such as velocity and can
also project vectors normal or tangential to the base object. Streamlines allow the users to see the simulated results of
the airflow over the object.

Velocity vectors on a propeller

Users can also
make the colour map on their testing
object to see the effect of air or other
variables. The colour map shown below is
of a 3D model of a car being tested for
pressure distribution on different locations.

Making charts in CFD Post

This ANSYS
tutorial also looks into the charts that
can be obtained from CFD-Post to better understand the results. In CFD post
the users can get a graph to determine the relationship between two variables.

In ANSYS post
processing, one of the three types of graphs
can be obtained.

The XY standard graph based on the line locators

The XY transient or sequence graph which is used to plot an expression, usually time vs any other variable at a point locator. This type of graph is also used to show the transient variation of a variable at a point on the graph.

Histograms can also be made in ANSYS. They can be based on any location that contains multiple data locations and can easily make plots of a variable divided into the small increments on the X-axis vs the frequency of occurrence on the Y-axis.

Other useful features and tools

ANSYS also has a
timestep sector that enables the users to post-process the transient results in
the result of the file and then different selector timesteps from the selector.
A full animation video for transient
solutions can also be made, and the video is savable in multiple different
formats.

The quick editor
in ANSYS postprocessing provides a quick way to change the primary values
connected with each object. The probe
allows the users to pick a point from the viewer and probe a variable value at that point.

Typical ANSYS keyframe animation procedure

Load the first timestep via the timestamp
selector

Create necessary plots and positions for your
object

Create the first keyframe for the animation

Load the last timestep

If needed, you can change the view and plots

Then create the second keyframe

Now select the first keyframe and set the needed number of frames

This is the number of frames between the first
and the second keyframes. The higher the number of frames, the smoother the
animation but would require more computing power

For
instance, if you have a total of 50
timesteps, then setting the number of frames to 58 will produce a total of 50 frames
(48 plus first and the last).

Now set the movie option

Rewind the first keyframe and click play.

In ANSYS CFD post-processing, the user can post-process their results in many different methods. This comprehensive ANSYS tutorial has compiled most commonly used post-processing techniques and features in ANSYS CFD Post. If you want to look into more details, visit us back soon.

Sohaib Alam is an Undergraduate at the University of Sunderland specializing in Mechanical Engineering. Sohaib specializes in Physics among many other engineering subject matter. He focuses his writing on ANSYS and AutoCAD Inventor.

Sohaib Alam is an Undergraduate at the University of Sunderland specializing in Mechanical Engineering. Sohaib specializes in Physics among many other engineering subject matter. He focuses his writing on ANSYS and AutoCAD Inventor.